This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.

This frame from an animation from NASA's Mars rover Curiosity shows the rover drilling into rock target 'Cumberland.' The drilling was performed during the 279th Martian day, or sol, of the Curiosity's work on Mars (May 19, 2013).

This image from the Mars Hand Lens Imager on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). The tool is a motorized, wire-bristle brush on the turret at the end of the rover's arm.

The two bodies in this portion of an evening-sky view by NASA's Mars rover Curiosity are Earth and Earth's moon. The rover's Mast Camera (Mastcam) imaged them in the twilight sky of Curiosity's 529th Martian day, or sol (Jan. 31, 2014).

This global map of Mars was acquired on Oct. 28, 2008, by the Mars Color Imager instrument on NASA's MRO. One global map is generated each day to forecast weather conditions for the entry, descent and landing of NASA's Curiosity rover.

Gale Crater on Mars, where NASA's Curiosity rover is set to land, belongs to a family of large, very old craters shown here on this elevation map. The data come from the Mars Orbiter Laser Altimeter instrument on NASA's Mars Global Surveyor.

This is a close-up view of the northern two-thirds of one of the quadrangles (number 50) that were mapped onto the landing region of NASA's Curiosity rover; background image obtained by NASA's Mars Reconnaissance Orbiter.

This image shows the topography, with shading added, around the area where NASA's Curiosity rover is slated to land on Aug. 5 PDT (Aug. 6 EDT). The red oval indicates the targeted landing area for the rover known as the 'landing ellipse.'

This graphic shows the flux of radiation detected by NASA's Mars Science Laboratory on the trip from Earth to Mars; the spikes in radiation levels occurred because of large solar energetic particle events caused by giant flares on the sun.

This set of artist's concepts shows NASA's Mars Science Laboratory cruise capsule and NASA's Orion spacecraft, which is being built now at NASA's Johnson Space Center and will one day send astronauts to Mars.

As of June 2012, the target landing area for NASA's Mars Science Laboratory mission is the ellipse marked on this image of Gale Crater. The ellipse is about 12 miles long and 4 miles wide (20 kilometers by 7 kilometers).

The landing target area for Curiosity, the big rover of NASA's Mars Science Laboratory mission, has been revised, reducing the area's size. It also puts the center of the landing area closer to Mount Sharp.

This image shows changes in the target landing area for Curiosity, NASA's Mars Science Laboratory rover. The larger ellipse for the target area has been revised to the smaller ellipse centered nearer to the foot of Mount Sharp, inside Gale Crater.

NASA's Mars Science Laboratory mission team members ran mobility tests on the test rover called 'Scarecrow' on sand dunes near Death Valley, Ca. in early May 2012 in preparation for operating the Curiosity rover, currently en route to Mars.

An in-flight camera check produced this out-of-focus image when NASA's Mars Science Laboratory spacecraft turned on illumination sources that are part of the Curiosity rover's Mars Hand Lens Imager (MAHLI) instrument.

Curiosity, the big rover of NASA's Mars Science Laboratory mission, will land in August 2012 near the foot of a mountain inside Gale Crater. The mission's project science group is calling the mountain Mount Sharp.

A NASA Mars Science Laboratory test rover called the Vehicle System Test Bed, or VSTB, at NASA's Jet Propulsion Laboratory, Pasadena, CA serves as the closest double for Curiosity in evaluations of the mission's hardware and software.

During pre-flight testing in March 2011, the Mars Hand Lens Imager (MAHLI) camera on NASA's Mars rover Curiosity took this image of the MAHLI calibration target under illumination from MAHLI's two ultraviolet LEDs (light emitting diodes).

During pre-flight testing, the Mars Hand Lens Imager (MAHLI) camera on NASA's Mars rover Curiosity took this image of the MAHLI calibration target from a distance of 3.94 inches (10 centimeters) away from the target.